/*
** $Id: lparser.h,v 1.76.1.1 2017/04/19 17:20:42 roberto Exp $
** Lua Parser
** See Copyright Notice in lua.h
*/

#ifndef lparser_h
#define lparser_h

#include "llimits.h"
#include "lobject.h"
#include "lzio.h"

/*
** Expression and variable descriptor.
** Code generation for variables and expressions can be delayed to allow
** optimizations; An 'expdesc' structure describes a potentially-delayed
** variable/expression. It has a description of its "main" value plus a
** list of conditional jumps that can also produce its value (generated
** by short-circuit operators 'and'/'or').
*/

/* kinds of variables/expressions */
typedef enum {
  VVOID, /* when 'expdesc' describes the last expression a list,
            this kind means an empty list (so, no expression) */
  VNIL, /* constant nil */
  VTRUE, /* constant true */
  VFALSE, /* constant false */
  VK, /* constant in 'k'; info = index of constant in 'k' */
  VKFLT, /* floating constant; nval = numerical float value */
  VKINT, /* integer constant; nval = numerical integer value */
  VNONRELOC, /* expression has its value in a fixed register;
                info = result register */
  VLOCAL, /* local variable; info = local register */
  VUPVAL, /* upvalue variable; info = index of upvalue in 'upvalues' */
  VINDEXED, /* indexed variable;
               ind.vt = whether 't' is register or upvalue;
               ind.t = table register or upvalue;
               ind.idx = key's R/K index */
  VJMP, /* expression is a test/comparison;
           info = pc of corresponding jump instruction */
  VRELOCABLE, /* expression can put result in any register;
                 info = instruction pc */
  VCALL, /* expression is a function call; info = instruction pc */
  VVARARG /* vararg expression; info = instruction pc */
} expkind;

#define vkisvar(k) (VLOCAL <= (k) && (k) <= VINDEXED)
#define vkisinreg(k) ((k) == VNONRELOC || (k) == VLOCAL)

typedef struct expdesc {
  expkind k;
  union {
    lua_Integer ival; /* for VKINT */
    lua_Number nval; /* for VKFLT */
    int info; /* for generic use */
    struct { /* for indexed variables (VINDEXED) */
      short idx; /* index (R/K) */
      lu_byte t; /* table (register or upvalue) */
      lu_byte vt; /* whether 't' is register (VLOCAL) or upvalue (VUPVAL) */
    } ind;
  } u;
  int t; /* patch list of 'exit when true' */
  int f; /* patch list of 'exit when false' */
} expdesc;

/* description of active local variable */
typedef struct Vardesc {
  short idx; /* variable index in stack */
} Vardesc;

/* description of pending goto statements and label statements */
typedef struct Labeldesc {
  TString* name; /* label identifier */
  int pc; /* position in code */
  int line; /* line where it appeared */
  lu_byte nactvar; /* local level where it appears in current block */
} Labeldesc;

/* list of labels or gotos */
typedef struct Labellist {
  Labeldesc* arr; /* array */
  int n; /* number of entries in use */
  int size; /* array size */
} Labellist;

/* dynamic structures used by the parser */
typedef struct Dyndata {
  struct { /* list of active local variables */
    Vardesc* arr;
    int n;
    int size;
  } actvar;
  Labellist gt; /* list of pending gotos */
  Labellist label; /* list of active labels */
} Dyndata;

/* control of blocks */
struct BlockCnt; /* defined in lparser.c */

/* state needed to generate code for a given function */
typedef struct FuncState {
  Proto* f; /* current function header */
  struct FuncState* prev; /* enclosing function */
  struct LexState* ls; /* lexical state */
  struct BlockCnt* bl; /* chain of current blocks */
  int pc; /* next position to code (equivalent to 'ncode') */
  int lasttarget; /* 'label' of last 'jump label' */
  int jpc; /* list of pending jumps to 'pc' */
  int nk; /* number of elements in 'k' */
  int np; /* number of elements in 'p' */
  int firstlocal; /* index of first local var (in Dyndata array) */
  short nlocvars; /* number of elements in 'f->locvars' */
  lu_byte nactvar; /* number of active local variables */
  lu_byte nups; /* number of upvalues */
  lu_byte freereg; /* first free register */
} FuncState;

LUAI_FUNC LClosure* luaY_parser(lua_State* L, ZIO* z, Mbuffer* buff, Dyndata* dyd, const char* name, int firstchar);

#endif
